Florida health officials’ response this summer to the first identified cases of local transmission and the first identified outbreak of Zika virus infection in the continental United States, including aggressive mosquito control efforts, helped to interrupt local transmission and reduce the effect on the community, including pregnant women.

Image/CDC

During late June through early August, 29 people were identified as having been infected with Zika virus through local mosquito-borne transmission, including 28 in Miami-Dade County and one in Broward County. Two cases were considered to be isolated with evidence of further transmission. However, the Florida Department of Health (FL DOH) identified an area of the Wynwood neighborhood with a cluster of cases, indicating ongoing spread of Zika virus by mosquitoes. Surveillance data showed intense transmission at a worksite and in the community. Although the outbreak was focalized, it continued to spread despite intense ground-based mosquito elimination efforts. Transmission rapidly ceased after Florida health officials implemented an aerial spraying plan that included use of the pesticides naled and bacillus Thuringensis to kill both adult mosquitoes and larva.

“After mosquitoes persisted and infections continued despite ground-based spraying, aerial spraying knocked down mosquitos rapidly and was associated with interrupting transmission of Zika in Wynwood,” said CDC Director Tom Frieden, M.D., M.P.H. “When faced with the potentially devastating outcomes of microcephaly or other serious brain defects that Zika can cause during pregnancy, we must use the best available tools to prevent infection. According to EPA assessments, when used properly, aerial spraying with naled for mosquito control doesn’t pose a risk to people or the environment.”

No new cases of locally transmitted Zika have been reported in the Wynwood-designated area since early August. As of September 19, the FL DOH has determined that active Zika virus transmission is no longer ongoing in the Wynwood area.

Today, FL DOH reported three new non-travel related cases in Miami-Dade County, which are all associated with the Miami Beach investigation, bringing the total to 95.